The present invention relates to antiperspirant compositons and, more particularly, to antiperspirant formulations suitable for aerosol application.
It is well known in the art to provide an antiperspirant formulation in the form of a cream, a stick, or a roll-on. However, these products have certain disadvantages, as they may leave an undesirable feel on the skin and may contain an excessive quantity of alcohol and water. More recently, aerosols under pressure have become popular as a convenient form for application of antiperspirant formulations to the skin. Aerosol antiperspirant and deodorant products not occupy a majority of the market for antiperspirant and deodorant products.
An aerosol product which possesses the attractive cosmetic properties and convenience benefits of currently available aerosol deodorant products and which additionally possesses substantial antiperspirant effects without excessive skin irritation would be highly desirable. Since the known inorganic astringent salts possess far greater antiperspirant activity than the organic astringent salts heretofore suggested for aerosol use, the inorganic salts must be used, despite the formulation problems involved, to provide such a product.
Among the most effective astringent inorganic salts are aluminum chloride and aluminum chlorhydrate. Aluminum chlorhydrate, also known as aluminum chlorhydroxide complex or basic aluminum chloride, has an approximate atomic ratio of aluminum to chlorine of 2:1, e.g., 2.1:1 to 1.9:1, and an empirical formula of Al.sub.2 (OH).sub.5 Cl, existing as a hydrate in solid form.
The efficacy of an antiperspirant composition is largely dependent upon the relative activity of the astringent salt employed therein. However, skin irritation can result from the low pH of many conventional antiperspirant formulations. It has been found that urea is very effective in reducing skin irritation caused by these formulations without reducing their efficacy. However, the large particle size and hygroscopicity of urea so far has prevented its use in dry aerosol antiperspirant products.
Accordingly, it is a primary object of this invention to provide improved aerosol antiperspirant compositions.
It is a further object of this invention to provide a dry aerosol antiperspirant formulation which may be applied in powder form, exhibits a high degree of antiperspirant activity and minimizes skin irritation.
It is a more specific object of this invention to provide dry aerosol antiperspirant formulations having desirable spray characteristics, relative freedom from valve clogging, and which contain highly effective levels of inorganic astringent salts while minimizing skin irritation.